Apparatus for cleaning economizer tubes



June 17, 1930. J. E. BELL APPARATUS FOR CLEANING ECONOMIZER TUBES FiledSept. 1'7, 1923 2 Sheets-Sheet l n mini.

INVENTStK ATTORNEY Patented June .17, 1930 JOHN E. BELL, 0F BROOKLYN,NEW YORK,

TION, OF NEW YORK, N. Y., A

ASSIGNOR TO FOSTER WHEELERCORPORA- CORPORATION OF NEW YORK APPARATUS FORCLEANING ECONOMIZER TUBES Application filed September 17, 1923. SerialNo. 663,106.

My present invention relates to fiuid heating apparatus of the type inwhich the fluid heated is passed through tubes the outer surfaces ofwhich are swept by heating gases,

and the general object of the invention is to provide such apparatuswith elfcctive provisions for removing soot or furnace dust deposited onthe outer surfaces of the tubes from the furnace heating gases, whilepermitting a relatively close spacing of the tubes, and relativelysimple end connections between tubes connected in series.

The invention was primarily devised, and is especially adapted for usein economizers comprising a bank or banks of closely spaced tubes, eachof which is externally corrugated or provided with alternatingcircumferential ribs and grooves increasing the heat absorbing surfaceof the tube. In such apparatus a relatively close spacing of the tubesis practically essential to reduce the bulk and cost of apparatus ofgiven capacity and the close spacing of the tubes and their corrugatedexternal surfaces makes efi'ective cleaning provisions absolutelyessential to the continued operation of the apparatus.

In accordance with the present invention I employ soot blowing pipesreceiving a suitable cleaning fluid under pressure as air or steam, anddischarging the cleaning fluid through orifices distributed along thelength of each pipe, and arrange these soot blowing pipes in the bank oftubes, in effect by removing one of the heating tubes to make room foreach soot blowing pipe which thus occupies the position in the bank oftubes which otherwise would be occupied by one of the heating tubes.Since in the type of economizer forwhich my invention was primarilydevised, and in analogous heat exchange apparatus the fluid heatedordinarily passes from one side of the bank oftubes to the otherserially through tubes at difierent distances from the sides of thebank, the replacement of any one heating tube by a soot blowing pipenecessarily involves a change in the end connections to adjacent heatingtubes, and my invention comprises a novel arrangement of suchconnections whereby the desired general conditions of flow of the fiuidheated are maintained, and changes in the general design of theapparatus are avoided.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification; for a better understanding of the inventionhowever, its advantages and specific objects attained with its use,reference should be had to the accompanying drawings and descriptivematter in which I haveillustrated and described preferred embodiments ofmy invention.

Of the drawings:

Fig. -1 is an elevation of an economizer with parts broken away and insection;

Fig. 2 is a section on the line 2-2 of Fig. 1;

. Fig. 3 is a partial section on the line 3-3 of Fig. 2; g

Fig. 4 is a partial section on the line 44 of Fig. 2;

Figs. 5 and 6 are views generally similar to Figs. 3 and 4,respectively, illustrating a modified construction;

Fig. 7 is a partial section on the line 77 of Fig. 5; y

Fig. 8 is a partial section on the line 88 of Fig. 1; and

Fig. 9 is a transverse section through one of the soot blower pipes.

In Figs. 1 to 4 of the drawings I have illus-v trated the use of mypresent invention in an economizer comprising a casing A having acentral partition B providing up and down passes for the heating gasesconnected together attheir upper ends and communicating at their lowerends with a suitable inlet and outlet, respectively, for the heatinggases. In each pass of the economizer as shown, there is a bank ofhorizontally disposed tubular heating elements 0. These ele'- mentspreferably consist each of an inner tube C of wrought metal, and anouter externally corrugated casing formed of cast iron sections, C asshown in Fig. 8. The casing A is advantageously formed as shown ofinner' and outer metal walls with a space between them packed withSil-o-cel or analogous material. Preferably as illustrated, the innersides of the side wall of the casing and the are each connected sides ofthe partition 13 are corrugated to correspond to the arrangement of thetubes C in horizontal rows with the tubes in adjacent rows staggeredwith respect to one another, thereby avoiding a laning action of theheating gases at the sides of the tube banks.

At the front end of the economizer, the top row tubes 0 in both banksare connected to an intermediate header D g; the bottom rows of tubes Cin one pass water inlet header DA, and the bottom row of tubes in theother pass are connected to the water outlet header DB. In each pass thetubes C in each intermediate horizontal row at one end of the economizerto a corresponding tube C in the row above, and at the other end of theeconomizer the tubes are connected each to a corresponding tube C in therow below. As shown these connections are all made by return bends orheader boxes E at the front end of the economizer, and by similar returnbends or header boxes F at the other end of the economizer, except whenthe connections are made by special connectors EA and FA as hereinafterexplained. Owing to the staggered arrangement of the tubes in adjacenthorizontal rows, the return bends E and F are inclined to the verticalas shown in Figs. 3 and 4.

Soot blower pipes H are interspersed among the tubes C in such fashionthat the tubes C and pipes H in each pass of the economizer form a bankof uniformly spaced tubular elements composed mainly of heating tubes O.The pipes H are sufficiently numerous and so distributed in the bankthat the cleaning jets discharged by them will adequately clean all ofthe heating tubes. As shown there are four pipes H in each bank arrangedin pairs with one pipe in each pair directly above the other pipe of thepair, though the number of pipes H employed and their arrangement may bevaried as conditions make desirable.

In the economizer construction illustrated, the return bends E and F andthe special connectors EA and FA, connect the various heater tubes C toform a plurality of separate paths of flow between the headers to whichthe tubes C in the top and bottom rows are directly connected. Ingeneral, each path of flow comprises a vertical zigzag row of tubes C,including one tube C in each horizontal tube row, but with the describedarrangement the two vertical zigzag rows which include the pipes H, eachcontains two less tubes C than the other rows. The fluid heated ispassed from the tube G above each pipe H into the tube C immediatelybelow it in the same vertical row, through a tube C immediatelyalongside the soot blower pipe, by means of a pair of-special endconnectors EA and FA, connected to the opposite ends of the lastmentioned tube C. The connecare connected to a.

tor EA is in the form of a triangular shaped box and connects the lastmentioned tube C to the two tubes G in the horizontal row above thecorresponding pipe H, which are in the same zigzag vertical rows withthe pipe H and the tube C alongside it to which the connector EA isconnected. The connector FA which may be identical in construction withthe connector EA, connects the tube C alongside the soot blower pipe Hto the two tubes G in the horizontal row below the pipe H which are inthe same zigzag vertical rows with the tubes above the soot blower pipeto which the connector EA is connected. With this arrangement each tubeC, to the ends of which connectors EA and FA are connected, forms inefiect, a common portion of two side by side and otherwise separatepaths of flow for the fluid heated from one side of the tube to theother. These two paths of flow are of the same length as the pathsformed by the vertical tube row not containing or adjacent the pipes H,but the velocity of flow through each tube 0 forming a common part ofthe two paths of flow is double that through the other tubes G in therow.

The soot blowing provisions including the pipes H are of well knowntype. Each pipe H is mounted in hearings to permi it to be rotated bymeans of a sheave and chain operated gear H and thus rotate itsdischarge outlets H about the pipe axis. Preferably each dischargeoutlet H is formed by a nozzle part as shown in Fig. 9, which is adaptedto give high velocity to the jet of cleaning fluiddischarged through it.The pipes H are connected to cleaning fluid supply piping I whichcomprises a nonrotatable portion I in alignment with, and through whichsteam, or other cleaning fluid is passed at suitable pressure into eachrotatable pipe H. The end of each pipe H remote from the correspondingpipe portion I, is closed.

with the described construction I am enabled to incorporate approved andeffective soot blowing provisions in a bank of closely spaced tubesproviding the usual multiple paths of flow for the fluid heated, withoutchanging the general design or capacity of the apparatus, and withoutrequiring new or additional structural elements other than the simplespecial end connecting parts EA and FA which are duplicates of oneanother, and the only change in operation of the apparatus is that theflow velocity through each tube connected at one end to a connectionmember .EA and at its opposite end to a connection member FA, isdoubled. The disposition of these end connectors EA and FA in the spaceavailable to receive them causes no difficulty notwithstanding thelimited character of that space.

Soot blowing provisions arranged in a bank of tubes as disclosed herein,are especially effective when those tubes comprise externally corrugatedcasings C of cast iron, as in the preferred construction illustrated,because of the manner in which the corrugation ribs and grooves defineand direct the eddy currents of the intertube tube space atmospherewhich are induced by the cleaning fluid jets discharged through the sootblower orifices H. When a jet of fluid is'discharge-d with substantialvelocity into the atmosphere, the jet sets up eddy currents in the formof whirls, all about the axis of the jet, in planes intersecting theaxis of the jet. With the described arrangement, the corrugations andribs of the elements define flow channels or paths of flow for the eddycurrents whereby the eddy current whirls produced are made mainlytransverse in direction to the length of the tubular ele ments C, asindicated by the arrows in Fig. 1. With a close spaced tube arrangement,the cleaning fluid jet discharged through an orifice H is substantiallyarrested, and its energy dissipated within a short distance from thesoot blower pipe from which the jet issues, and the direct cleaningeffect of the jet is comparatively small. The whirls or eddy currentsset up by the jets however, extend outward from the soot blower tubefrom which the jet issues for a distance considerably greater than doesthe jet'proper, and with a suitably high jet velocity and volume, theeddy currents have sufficient ve locity to exert a tube cleaning effectwhich is much greater than the directcleaning effect of the jetproper.This indirect cleaning effeet is mainly instrumental in making thedescribed soot blowing provisions effective. to secure the desiredcleaning effect, a high et velocity is required and in practice when thefluid heating apparatus is associated with a steam generating plant,steam at the boiler pressure is utilized as the cleaning fluid. Withsteam at a normal boiler pressure of 150 lbs. per square inch or above,the jets discharged directly against bare wrought metal tubes would cutinto the tubes, and might dangerously weaken them in a comparativelyshort time. When the tubes are encased in cast metal however, as in thepreferred construction illustrated, the cutting action is of noimportance partly because the cast iron is less subject to the cuttingaction than is wrought iron or steel, but mainly because a cuttingefl'ect which may be sufficient in extent to dangerously weaken a baretube of wrought metal, does no particular harm to the cast iron casingsections C wnich may be eaten or cut away to a considerable extentwithout weakening the tubular elements or appreciablyreducing their"heat absorbing areas.

In Figs 5, 6, and 7 an alternative arrangement is employed in which thetubes C in each pass are arranged in two banks, one above the other,which are shown as spaced apart, though this is not essential. ."Thetubes C in the bottom row of each upper bank are each connected to acorresponding tube in the top row of the lower bank by a connector K orL. The general inclination to the vertical of the end connectors E andF, made necessary by the staggered arrangement of the tubes C inadjacent horizontal rows, is reversed in one bank with respect to thatfor the other bank. Special end connectors FB are employed in thisconstruction only at the rear end of the economizer, and each of theseis elongated to connect the tubes C in the same zigzag vertical rowimmediately above and below a corresponding pipe H. The eifect of thisis to reverse the direction of flow through one of the tubes C connectedby each connector FB with respect to the other tubes C in the samehorizontal row. With one or more pairs of soot blower pipes H in eachvertical row and a corresponding pair or pairs of end connectors FB, sothat the direction of flow is reversed an even number of times in eachvertical row, the direction of flow through the tubes C at the ends ofthe row is not changed. The inclination of the end connections E andFconnecting tubes C in which the direction of flow is reversed, is thereverse of the ad acent connections E and F. The special end connectionsFB each comprises a port on parallel to the end connections alongside itand an oppositely inclined portion. As the drawings indicate, thespecial arrangement of end connections in the construction shown inFigs. 5, 6, and 7 is compact and well adapted to the space requirements.The adjacent tubes G in the zigza vertical rows in which there are nopipes are connected at the front end of-the apparatusby elongatedconnectors K, and thetubes in each row in which there are pipes'H areconnected at the head end of the economizer by an elongated connector L.In Figs. 5, 6, and 7, the velocity of flow through the various tubes inany vertical row is the same, but the path of flow formed by the varioustubes 0 in each vertical row containing soot blower pipes is shorter bythe length of two tubes C, than the flow paths formed by anothervertical row of tubes.

While in accordance with the provesions of the statutes I haveillustrated and described the best forms ofmy invention now known tome,it will be apparent to those skilled in the art that changes may be madein the form of the apparatus disclosed without departing from the spiritof my invention as set forth in the appended claims.

Having now described my invention, what bank of tubular elements one ormore of' which are soot blower pipes while the remainder form conduitsfor the fluid to be heated and connections to the ends of the conduitelements connecting said elements in rows and thereby forming multiplepaths of flow for the fluid to be heated, from one side of the bank tothe other, each of which paths .includes all of the conduit elements inthe corresponding row, said connections including parts connecting thetwo conduit elements at opposite sides of each soot blower pipe and inthe same row with the latter through a conduit element in an adjacentrow.

2. Fluid heating apparatus comprising in other soot blower pipe, andconnections to the ends of the conduit elements connecting all of thesaid elements in each of said row for series flow therethrough.

Signed at New York city, in the county of New York and State of NewYork, this 14th day of September, A. D. 1923.

JOHN E. BELL.

